All discharges are categorized into five hospitalization types (i.e., service lines) in the following hierarchical order: maternal/neonatal, mental health/substance abuse, injury, surgical, and medical.

Maternal and neonatal discharges are defined using the following Clinical Classification Software (CCS) categories for the principal ICD-9-CM diagnosis:

• Maternal:
  • 176: Contraceptive and procreative management
  • 177: Spontaneous abortion
  • 178: Induced abortion
  • 179: Postabortion complications
  • 180: Ectopic pregnancy
  • 181: Other complications of pregnancy
  • 182: Hemorrhage during pregnancy; abruptio placenta; placenta previa
  • 183: Hypertension complicating pregnancy; childbirth and the puerperium
  • 184: Early or threatened labor
  • 185: Prolonged pregnancy
  • 186: Diabetes or abnormal glucose tolerance complicating pregnancy; childbirth; or the puerperium
  • 187: Malposition; malpresentation
  • 188: Fetopelvic disproportion; obstruction
  • 189: Previous C-section
  • 190: Fetal distress and abnormal forces of labor
  • 191: Polyhydramnios and other problems of amniotic cavity
  • 192: Umbilical cord complication
  • 193: OB-related trauma to perineum and vulva
  • 194: Forceps delivery
  • 195: Other complications of birth; puerperium affecting management of mother
  • 196: Normal pregnancy and/or deliver
• Neonatal:
  • 218: Liveborn
  • 219: Short gestation; low birth weight; and fetal growth retardation
  • 220: Intrauterine hypoxia and birth asphyxia
  • 221: Respiratory distress syndrome
  • 222: Hemolytic jaundice and perinatal jaundice
  • 223: Birth trauma
  • 224: Other perinatal conditions

Mental health/substance abuse discharges are defined using the following CCS categories for principal ICD-9-CM diagnosis:

• 650: Adjustment disorders
• 651: Anxiety disorders
• 652: Attention-deficit, conduct, and disruptive behavior disorders
• 653: Delirium, dementia, and amnestic and other cognitive disorders
• 654: Developmental disorders
• 655: Disorders usually diagnoses in infancy, childhood, or adolescence
• 656: Impulse control disorders, NEC
• 657: Mood disorders
• 658: Personality disorders
• 659: Schizophrenia and other psychotic disorders
• 660: Alcohol-related disorders
• 661: Substance-related disorders
• 662: Suicide and intentional self-inflicted injury
• 663: Screening and history of mental health and substance abuse codes
• 670: Miscellaneous disorders

Injury discharges are identified using the principal ICD-9-CM diagnosis and a scheme recommended by Safe States Alliance, previously known as the State and Territorial Injury Prevention Directors Association (STIPDA). The table below lists the diagnosis codes in the range 800-999 used to identify injuries.

• Includes:
  • 800-909.2, 909.4, 909.9: Fractures; dislocations; sprains and strains; intracranial injury; internal injury of thorax, abdomen, and pelvis; open wound of the head, neck, trunk, upper limb, and lower limb; injury to blood vessels; late effects of injury, poisoning, toxic effects, and other external causes, excluding those of complications of surgical and medical care and drugs, medicinal or biological substances.
  • 910-994.9: Superficial injury; contusion; crushing injury; effects of foreign body entering through orifice; burns; injury to nerves and spinal cord; traumatic complications and unspecified injuries; poisoning and toxic effects of substances; other and unspecified effects of external causes.
  • 995.5-995.59: Child maltreatment syndrome.
  • 995.80-995.85: Adult maltreatment, unspecified; adult physical abuse; adult emotional/ psychological abuse; adult sexual abuse; adult neglect (nutritional); other adult abuse and neglect.
• Excludes:
  • 909.3, 909.5: Late effect of complications of surgical and medical care and late effects of adverse effects of drug, medicinal, or biological substance.
  • 995.0-995.4, 995.6-995.7, 995.86, 995.89: Other anaphylactic shock; angioneurotic edema; unspecified adverse effect of drug, medicinal and biological substance; allergy, unspecified; shock due to anesthesia; anaphylactic shock due to adverse food reaction; malignant hyperpyrexia or hypothermia due to anesthesia.
  • 996-999: Complications of surgical and medical care, not elsewhere classified.

It should be noted that the above definition of injury includes five diagnosis codes that are also included under two CCS diagnosis categories used for the definition of the mental health/substance abuse service line:

• CCS = 660 (Alcohol-related disorders): diagnosis 9800 (toxic effect of ethyl alcohol)
• CCS = 661 (Substance-related disorders): diagnoses 96500 (poisoning by opium), 96501 (poisoning by heroin), 96502 (poisoning by methadone), 96509 (poisoning by other opiate).

Because of the hierarchical ordering used to assign discharges to service lines, discharges with one of these five principal ICD-9-CM diagnosis codes were assigned to the mental health/substance abuse service line and not the injury service line.

Surgical discharges are identified by a surgical DRG. The DRG grouper first assigns the discharge to a Major Diagnostic Category (MDC) based on the principal diagnosis. For each MDC there is a list of procedure codes that qualify as operating room procedures. If the discharge involves an operating room procedure, it is assigned to one of the surgical DRGs within the MDC category; otherwise it is assigned to a medical DRG.

Medical discharges are identified by a medical DRG. The DRG grouper first assigns the discharge to an MDC based on the principal diagnosis. For each MDC there is a list of procedure codes that qualify as operating room procedures. If the discharge involves an operating room procedure, it is assigned to one of the surgical DRGs within the MDC category; otherwise it is assigned to a medical DRG. If the DRG indicated the information on the record was ungroupable (i.e., not identifiable as medical or surgical), then the discharge was assumed to be medical. This rarely occurred (less than 0.1 percent of total discharges).